import java.io.*;
import java.util.*;

public class Queue extends Vector {

    public int serveNextCustomerAt;

    public void enqueue(Object o) {
	super.add(o);
    }

    public Object dequeue() {
	Object temp;
	try {
	    temp = super.firstElement();
	    super.remove(0);
	} catch(NoSuchElementException e) {return null;}
	return temp;	    
    }

}
